Taper under taper plate to increase side force on the movable plate

ABSTRACT

The present invention increases the capacity and resistance to closure of the draft gear assembly by providing an angled bottom surface on the tapered plates intermediate of the inner and outer friction surface in the area where the taper plate contacts the third horizontal rib of the housing. Providing an angle on the bottom edge surface of the tapered plates in this area increases the side force on the movable plates during the application of a buffing shock to the draft gear assembly.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is closely related to and claims benefit fromU.S. Provisional Application Ser. No. 60/561,050 filed Apr. 8, 2004filed concurrently herewith.

FIELD OF THE INVENTION

The present invention relates, in general, to draft gear assemblies foruse in cushioning both buff and draft shocks normally encountered byrailway rolling stock during make-up and operation of a train consist ona track structure and, more particularly, the present invention relatesto a draft gear assembly having a tapered plate wherein a portion of thebottom surface which contacts the third lug of the housing is angled toincrease the side force on the movable plate which increases the draftgear assembly's resistance to closure and increases the capacity of thedraft gear assembly.

BACKGROUND OF THE INVENTION

Draft gear assemblies which utilize friction-type clutch mechanisms toabsorb heat energy generated during service have been in widespread usein the railroad industry for many years to absorb both buff and draftshocks applied to the railway rolling stock. Many of such draft gearassemblies which were in use, prior to the present invention, are taughtin U.S. Pat. Nos. 2,916,163; 3,178,036; 3,447,693; and 4,645,187. Eachof the above-identified patents is owned by the assignee of the presentinvention. The teachings of each of these patents are all incorporatedinto the present application by reference thereto.

These draft gear assemblies are designed to receive coupler forces anddissipate them without damage to the car structure and lading. Theassemblies are disposed within an elongated opening located in thecenter sill member of the railway car along the longitudinal axisthereof and behind the shank, or innermost end, of the railway car'scoupling mechanism. In this position, these friction clutch type draftgear assemblies will absorb at least a relatively large portion of boththe buff and draft forces generated during service. Such buff and draftforces encountered by such railway cars are usually being applied in analternating manner to the center sill member during normal car operationon the track.

It is well recognized in the art that these draft gear assemblies mustbe provided with the capability of maintaining at least a certainminimum shock absorbing capacity both during making up a train consistand in-track service. Such minimum capacity has been specified by theAssociation of American Railroads (AAR) and is defined in the standardsissued by the AAR. For example, friction clutch type draft gearassemblies have a specified absolute minimum capacity rating of at least36,000 foot pounds. Any draft gear assembly with a capacity rating whichis determined to be below 36,000 pounds will not receive approval fromthe AAR for service on any railroad car which may be used ininterchange.

It is, likewise, important to note that the heat energy absorbing actionof the friction clutch mechanism must enable this minimum capacityrating to be readily achieved without exceeding a specified maximum500,000-pound reaction force, or pressure, being exerted on the centersill member of the railway car during both such make-up and operation ofsuch train consist. It has been found that such maximum reactionpressure is required to enable these high energy shocks to be readilyabsorbed without upsetting the end of the coupling member shank and/ordamaging other critical car components and/or lading that is beingtransported by such railway car.

In order for the manufacturers of such friction clutch type draft gearassemblies to meet the requirements of the railroad industry, with theever-increasing load carrying capacity of their modern day railroadcars, it has become of extreme importance to enhance the overall ratedcapacity of the friction-type draft gear assemblies as much as possible.This higher capacity rating being found necessary in order to minimizeany damage to such cars and/or the lading due to the increased forcesbeing exerted on the center sill member of the cars by the heavier loadssuch cars are now carrying.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to produce a draft gearassembly having an increased capacity and resistance to closure.

It is a further object of the invention to provide a frictionalcushioning means for a draft gear assembly wherein an additional sideforce is applied to the movable plates from the tapered plate.

It is yet a further object of the invention to provide a cushioningmeans for a draft gear assembly wherein an angle is provided on theportion of the bottom edge of the tapered plate which contacts the thirdrib of the housing and/or to the taper plates ear/lug which sits on thethird rib so as to increase the side force on the movable plate,increasing the capacity of the draft gear and providing a greaterresistance to closure.

It is an additional object of the invention to provide sufficientclearance between the angled edge surface of the tapered plate and theseat means of the draft gear assembly while accounting for wear of thecompressible cushioning element.

Briefly, and in accordance with the forgoing objects, the inventioncomprises a draft gear assembly comprising a housing closed at one endand open at the opposed end and having a rear portion adjacent theclosed end and a front portion adjacent the open end, a compressiblecushioning element centrally disposed within the rear portion abuttingthe housing end and extending longitudinally there from, a seat meansabutting the opposite end of the compressible cushioning element duringapplication and release of a force on the draft gear assembly, and afriction cushioning means positioned at least partially within saidfront portion of said housing for absorbing energy during a compressionof said draft gear assembly. The friction cushioning means includes apair of laterally spaced outer stationary plates having an outer surfacefor engaging the housing and an opposed inner friction surface, a pairof laterally spaced movable plates having an outer friction surface formovably engaging the outer stationary plates, an inner friction surfaceand at least one substantially flat edge intermediate said outerfriction and inner friction surfaces for engaging the seat means, a pairof laterally spaced tapered plates having an outer friction and an innerfriction surface wherein the outer friction surface movably andfrictionally engages the inner friction surface of the movable plate, apair of laterally spaced wedge shoes having an outer friction surfacefor movably and frictionally engaging an inner friction surface of thetapered plate, and a center wedge having a pair of matchingpredetermined tapered portions for engaging the tapered portion of thewedge shoe to initiate frictional engagement of said friction cushioningmeans and thereby absorb energy. The housing includes three horizontalribs for positioning and/or holding the components of the cushioningmeans. A spring release means is provided which engages andlongitudinally extends between the seat means and the center wedge forcontinuously urging the friction cushioning means outwardly from thecompressible cushioning means to release the friction cushioning elementwhen an applied force compressing the draft gear is removed.

The present invention increases the capacity and resistance to closureof the draft gear assembly by providing an angled bottom surface on thetapered plates intermediate of the inner and outer friction surface inthe area where the tapered plate contacts the third horizontal lug ofthe housing. Providing an angle on the bottom edge surface of thetapered plates in this area increases the side force on the movableplates during the application of a buffing shock to the draft gearassembly.

Although a number of objects and advantages of the present inventionhave been described in some detail above, various additional objects andadvantages of the draft gear assembly of the present invention willbecome more readily apparent to those persons who are skilled in the artfrom the following more detailed description of the invention,particularly, when such detailed description of the invention is takenin conjunction with both the attached drawing figures and with theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a draft gear assemblyof the invention incorporating one form of a presently preferredembodiment of a cushioning element for the draft gear assembly.

FIG. 2 is a longitudinal cross-sectional view of a draft gear assemblyof the invention incorporating an alternative embodiment of a cushioningelement for the draft gear assembly.

FIG. 3 is a longitudinal cross-sectional view of a draft gear assemblyof the invention incorporating an alternative embodiment of a hydrauliccushioning element for the draft gear assembly.

FIG. 4 is a perspective view of the draft gear housing illustrating thefirst, second, and third horizontal lugs.

FIG. 5 shows two different angles on the third rib.

DETAILED DESCRIPTION OF THE INVENTION

The draft gear assembly, according to the present invention, isinstalled in alignment with a railroad car center sill between a frontand a rear draft gear lug. A vertical yoke is connected to a couplershank by a draft key with a coupler horn spaced from a striking plateand with a front follower member within the yoke which is positionedadjacent to the front lugs, all substantially in accordance with theprior art conventional practice as illustrated in the aforementionedU.S. Pat. No. 2,916,163.

Prior to proceeding to the more detailed description of the variousembodiments of the instant invention, it should be pointed out that, forthe sake of clarity, identical components which have identical functionshave been identified with identical reference numerals throughout theseveral views that have been illustrated in the drawings.

Now reference is made, more particularly, to drawing FIGS. 1-4.Illustrated therein are the essential components a draft gear assembly,generally designated 10, used in a railway car (not shown). The assembly10 includes a housing, generally designated as 12. The housing 12 isopen at one end and has a rear portion 14 adjacent a bottom wall 16which closes the other end of housing 12. Rear portion 14 is providedfor receiving therein a compressible cushioning means, generallydesignated as 26. Housing 12 includes a front portion 18 adjacent theopen end. Front portion 18 is in open communication with the rearportion. Housing 12 additionally includes first, second, and thirdhorizontal ribs 20, 22, and 24 as shown in FIG. 4.

The compressible cushioning element 26 is centrally disposed within therear portion 14 and has one end thereof abutting at least a portion ofan inner surface 28 of the bottom wall 16 of housing 12. Thecompressible cushioning element 26 extends longitudinally from bottomwall 16 where the opposite end is placed into abutting relationship withat least a portion of one surface 30 of a seat means 32. Seat means 32is positioned within the housing 12 for longitudinal movement thereinfor respectively compressing and releasing the compressible cushioningelement 26 during application and release of a force on the draft gearassembly 10.

As shown in FIG. 1, the compressible cushioning element 26, according toone embodiment of the invention, comprises at least one and preferablyat least two springs 34, 35. FIG. 2 shows an alternative embodiment fora compressible cushioning element 26 which comprises an outer coilspring 36 and an inner rubber spring 37. FIG. 3 shows anotheralternative embodiment of the invention in which the compressiblecushioning element 26 is a hydraulic unit 38 such as taught in U.S. Pat.No. 3,447,693.

A friction cushioning means, generally designated as 40, is positionedat least partially within the front portion 18 of the housing 12. Thefriction cushioning means 40 absorbs energy during application of aforce sufficient to cause a compression of the draft gear assembly 10.

The friction cushioning means 40 includes a pair of laterally spacedouter stationary plates 42 having an outer surface 44 and an opposedinner friction surface 46. The outer surface 44 engages the housing 12.A pair of laterally spaced movable plates 48 of substantially uniformthickness is also provided. Movable plates 48 have an outer frictionsurface 50 and an inner friction surface 52 and at least onesubstantially flat edge 54 intermediate the outer friction surface 50and the inner friction surface 52 which edge 54 engages the seat means32. At least a portion of the outer friction surface 50 movably andfrictionally engages the inner friction surface 46 of the outerstationary plate 42. A pair of laterally spaced tapered plates 56 isprovided. The tapered plates 56 include an outer friction surface 58 andan inner friction surface 60. The outer friction surface 58 movably andfrictionally engages at least a portion of the inner friction surface 52of the movable plate 48. The tapered plates 56 include an angled ortapered edge 62 intermediate the outer friction surface 58 and the innerfriction surface 60. The angle of the tapered edge 62 may range from10-40 degrees. FIG. 5 shows two different angles for the tapered edge 62of the tapered plate 56. The laterally spaced outer stationary plates 42and the tapered plates 56 sit on the third horizontal rib 24 of thehousing 12. This angled or tapered edge 62 is in the area where thetapered plates 56 contact the third horizontal rib 24. Tapering the areaof the tapered plate where the tapered plate sits in the housingrequires the area under the third rib to be built up. This area is alsoaffected by the corner coil spring seat. Friction cushioning means 40further includes a pair of laterally spaced wedge shoes 64 which have atleast a portion of an outer friction surface 66 movably and frictionallyengaging at least a portion of the inner friction surface 60 of thetapered stationary plate 56. Wedge shoes 64 have at least a portion ofone edge 68 engaging seat means 32 and a predetermined tapered portion70 on an opposed edge thereof. A center wedge 72 is provided which has apair of matching tapered portions 74 for engaging the tapered portion 70of the wedge shoe 64 to initiate frictional engagement of the frictioncushioning means 40.

It has been discovered that providing an angle or taper 62 on the bottomsurface of the tapered plates 56 in the area that contacts the thirdhorizontal rib 24 of the housing 12, results in a greater side forcebeing applied to movable plates 56. Thus, the capacity of the draft gearand its resistance to closure is increased. A spring release means 76engages and extends longitudinally between the seat means 32 and thecenter wedge 72 for continuously urging the friction cushioning means 40outwardly from the compressible cushioning means 26 to release thefriction cushioning means 40 when an applied force compressing the draftgear assembly 10 is removed.

A draft gear typically has approximately 0.125″ clearance between thebottom edges of the taper plates 56 and the seat means 32. High loadingfrom the taper plate requires that the housing's bearing area and thecross-sectional area on the taper plate's ear remain equal to thepresent design so shear failures do not occur. As the draft gear wearsout, the assembled height of the spring type compressible cushioningelements 26 of FIGS. 1 and 2 increases, resulting in a reduced clearancebetween the bottom edges of the taper plates 56 and the seat means 32. Adraft gear nearly worn out has near zero clearance between the bottomedges of the taper plates 56 and the seat means 32. The presentinvention's new design criteria and assembly conditions are as follows:

For a 10 degree taper, approximately 0.176″ of clearance is provided.

For a 20 degree taper, approximately 0.364″ of clearance is provided.

For a 30 degree taper, approximately 0.5571″ of clearance is provided.

For a 40 degree taper, approximately 0.839″ of clearance is provided.

In operation, the buffing shock is transmitted from the coupler throughthe front follower to the central wedge 72, causing it to act throughthe wedge shoes 64 and thereby compress all of the cushioning elementssimultaneously. These parts will furnish sufficient cushioning for lightbuffing shocks. After suitable travel, however, the follower will comeagainst the outer ends of the movable plates 48 introducingenergy-absorbing friction between the movable plates 48 and thestationary plates 42 and 56 which have been pressed together by theaction of the wedge shoes 64. As this action continues, the pressurebetween the adjacent surfaces of the plates has been enormouslyincreased due to the fact that the wedge shoes 64 are loaded against thecushioning mechanism 40.

The energy absorption and dissipation through friction and compressionof the cushioning mechanism continues until the gear is closed includingcompression of cushioning element 26.

During release of the gear, the compressible cushioning element 26 ismaintained in alignment by the seat means 32.

Thus, the present invention has been described in such full, clear,concise and exact terms as to enable any person skilled in the art towhich it pertains to make and use the same. It will be understood thatvariations, modifications, equivalents, and substitutions for componentsof the specifically described embodiments of the invention may be madeby those skilled in the art without departing from the spirit and scopeof the invention as set forth in the appended claims.

1. A draft gear assembly having an increased capacity to cushion shocksencountered in railroad rolling stock, said draft gear assemblycomprising: (a) a housing closed at one end and open at the opposed end,said housing having a rear portion adjacent said closed end and a frontportion adjacent said open end, said front portion being in opencommunication with said rear portion; (b) a compressible cushioningelement centrally disposed within said rear portion with one end thereofabutting at least a portion of an inner surface of said closed end ofsaid housing, said compressible cushioning element extendinglongitudinally from said one end; (c) a seat means having at least aportion of one surface thereof abutting the opposite end of saidcompressible cushioning element during application and release of aforce on said draft gear assembly; (d) a friction cushioning meanspositioned at least partially within said front portion of said housingfor absorbing energy during a compression of said draft gear assembly,said friction cushioning means including (i) a pair of laterally spacedmovable plates having an outer friction surface and an inner frictionsurface and at least one substantially flat edge intermediate said outerfriction and inner friction surfaces, said one edge engaging said seatmeans, (ii) a pair of laterally spaced tapered plates positioned forfrictional engagement with at least a portion of said inner frictionsurface of said movable plates, said tapered plates having an outerfriction and an inner friction surface and at least one edgeintermediate said outer friction and inner friction surfaces, at least aportion of said at least one intermediate edge having an angled surface,said angle surface being capable of increasing the side force applied tosaid movable plates and increasing the capacity of the draft gear, (iii)a pair of laterally spaced wedge shoes having at least a portion of anouter friction surface movably and frictionally engaging at least aportion of an inner friction surface of said tapered plate, and at leasta portion of one edge engaging said seat means, and (iv) a center wedgehaving a pair of matching predetermined tapered portions for engagingsaid tapered portion of said wedge shoe to initiate frictionalengagement of said friction cushioning means and thereby absorb energyto cushion shocks encountered in railroad rolling stock.
 2. A draft gearassembly having an increased capacity as recited in claim 1 wherein saidhousing includes a first, second, and third horizontal rib and whereinsaid angled edge of said pair of laterally spaced tapered plates ispositioned on said third horizontal rib.
 3. A draft gear assembly havingan increased capacity as recited in claim 1 wherein the angle of saidangled edge of the tapered plate is approximately 10-40 degrees.
 4. Adraft gear assembly having an increased capacity as recited in claim 3wherein a clearance of approximately 0.176-0.839 inches is providedbetween said seat means and said angled edge of the tapered plate.
 5. Adraft gear assembly having an increased capacity as recited in claim 1wherein said cushioning means includes a pair of laterally spaced outerstationary plates having an outer surface for engaging said housing andan opposed inner friction surface for engaging said outer frictionsurface of said movable plates.
 6. A draft gear assembly having anincreased capacity as recited in claim 1 including a spring releasemeans engaging and longitudinally extending between said seat means andsaid center wedge for continuously urging said friction cushioning meansoutwardly from said compressible cushioning means to release saidfriction cushioning element when an applied force compressing said draftgear is removed.
 7. A friction cushioning means for a draft gearassembly to cushion shocks encountered in railroad rolling stock, saidfriction cushioning means comprising: (a) a pair of laterally spacedouter stationary plates having an outer surface for engaging a housingof said draft gear assembly and an opposed inner friction surface; (b) apair of laterally spaced movable plates having an outer friction surfaceand an inner friction surface, at least a portion of said outer frictionsurface movably and frictionally engaging said inner friction surface ofsaid outer stationary plate; (c) a pair of laterally spaced taperedplates, said tapered plates having an outer friction and an innerfriction surface and at least one angled edge intermediate said outerfriction and inner friction surfaces, said outer friction surfacemovably and frictionally engaging at least a portion of said innerfriction surface of said movable plate; (d) a pair of laterally spacedwedge shoes having at least a portion of an outer friction surfacemovably and frictionally engaging at least a portion of an innerfriction surface of said tapered plate, and at least a portion of oneedge engaging said seat means; and (e) a center wedge having a pair ofmatching predetermined tapered portions for engaging said taperedportion of said wedge shoe to initiate frictional engagement of saidfriction cushioning means and thereby absorb energy to cushion shocksencountered in railroad rolling stock.
 8. A friction cushioning meansfor a draft gear assembly as recited in claim 7 wherein said frictioncushioning means is positioned in a housing and wherein said housingincludes a first, second, and third horizontal rib and said intermediateangled edge of said pair of laterally spaced tapered plates ispositioned on said third horizontal lug.
 9. A friction cushioning meansfor a draft gear assembly as recited in claim 7 wherein the angle ofsaid intermediate angled edge of the tapered plate is approximately10-40 degrees.
 10. A friction cushioning means for a draft gear assemblyas recited in claim 9 wherein a seat means is provided beneath saidintermediate angled edge and a clearance of approximately 0.176-0.839inches is provided between said seat means and said intermediate anglededge of the tapered plate.
 11. A friction cushioning means forincreasing the capacity of a draft gear assembly to cushion shocksencountered in railroad rolling stock, said friction cushioning meanscomprising: (a) a pair of laterally spaced movable plates having anouter friction surface and an inner friction surface; (b) a pair oflaterally spaced tapered plates positioned for frictional engagementwith at least a portion of said inner friction surface of said movableplates, said tapered plates having an outer friction and an innerfriction surface and at least one angled edge intermediate said outerfriction and inner friction surfaces, said angled edge being capable ofincreasing the side force applied to said movable plates and increasingthe capacity of the draft gear; and (c) a pair of laterally spaced wedgeshoes having at least a portion of an outer friction surface movably andfrictionally engaging at least a portion of an inner friction surface ofsaid tapered plate, and at least a portion of one edge engaging saidseat means; and (d) a center wedge having a pair of matchingpredetermined tapered portions for engaging said tapered portion of saidwedge shoe to initiate frictional engagement of said friction cushioningmeans and thereby absorb energy to cushion shocks encountered inrailroad rolling stock.
 12. A friction cushioning means for increasingthe capacity of a draft gear assembly as recited in claim 11 whereinsaid friction cushioning means is positioned in a housing and whereinsaid housing includes a first, second, and third horizontal rib and saidintermediate angled edge of said pair of laterally spaced tapered platesis positioned on said third horizontal lug.
 13. A friction cushioningmeans for increasing the capacity of a draft gear assembly as recited inclaim 11 wherein the angle of said intermediate angled edge of thetapered plate is approximately 10-40 degrees.
 14. A friction cushioningmeans for increasing the capacity of a draft gear assembly as recited inclaim 13 wherein a seat means is provided beneath said intermediateangled edge and clearance of approximately 0.176-0.839 inches isprovided between said seat means and said intermediate angled edge ofthe tapered plate.
 15. A friction cushioning means for increasing thecapacity of a draft gear assembly as recited in claim 11 wherein saidcushioning means includes a pair of laterally spaced outer stationaryplates having an outer surface for engaging said housing and an opposedinner friction surface for engaging said outer friction surface of saidmovable plates.
 16. A friction cushioning means for increasing thecapacity of a draft gear assembly as recited in claim 11 including aspring release means engaging and longitudinally extending between aseat means and said center wedge for continuously urging said frictioncushioning means outwardly from said compressible cushioning means torelease said friction cushioning element when an applied forcecompressing said draft gear is removed.
 17. A friction cushioning meansfor increasing the capacity of a draft gear assembly as recited in claim11 wherein the area under the third rib which is positioned beneath thetapered area of the tapered plate is built up.